Corrugated fastener.



F. P. PRINDLE.

CORRUGATED FASTE'NER.

APPLICATION msn MAn.so.1916.

Patented. Apr. 16, 1918.

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FRANK P. PRINDLE, OF NEW BRITAIN, CONNECTICUT, ASSIGNOR T0 THE STANLEY WORKS, OF NEW BRITAIN, CONNECTICUT, A CORPORATION OF CONNECTICUT.

CORRUGATED FASTENER.

Specification of Letters Patent.

Patented Apr. 16, 1918.

Application led March 30, 1916. Serial No. 87,710.

' more efficient in operation than and as cheap to make as any other corrugated fastener known to me, and to such ends my invention consists in the corrugated fastener hereinafter specified.

This application is a continuation in part of my prior application, Serial #7,853, filed February 12, 1915.

In the accompanying drawings-n Figure 1 is a perspective view of a fastener embodying my invention;

Fig. 2 is a top plan view of such a fastener (drawn on an enlarged scale) Fig. 3 is a transverse sectional view taken on the line X-X of Fig. 1, and looking in the direction of the arrows, and

Fig. 4L is a cross-sectional view showing the beveled edge of the fastener.

My invention is capable of embodiment in different forms, and while I have chosen the best embodiment thereof known t0 me, such embodiment is to be regarded as typical only, and my invention is not to be confined thereto except as required by the Ascope of the appended claims.

Prior to my invention, previous corrugated fasteners, as far as known to me, have had one or more of the following disadvantages:

Where there have been straight or chisel points on the entering edge, they have been formed by the meeting of a single beveled surface with a vertical surface, and have thus not cut to the bestadvantage, making the fastener difficult to drive and liable to break the grain instead of making a clean Such rentrant portions have also been sharpened only by a single beveled surface meeting a perpendicular surface-a con-.-

struction which is both hard to drive and tends to tear the wood to some extent.

Where cutting points have been provided, they have been of such excessive length as to narrow and therefore weaken the body of the fastener. l

Such fasteners have either used a sinuous, curved shape in horizontal cross-section, with curved corrugations, a construction in which a large part of the cutting edge cuts across the grain of the wood when used to join the edges of boards, as is frequently done, and therefore tends to break the grain, or a V- shaped corrugation in horizontal cross-section was used, in which the cutting edge all had one level, which could take no adequate advantage of the V-shape corrugations.

Where cutting points having notches between them have been used in the prior art, the cutting edges formed in these rentrant portions have been curved, a construction which does not enter the wood to the best advantage, nor always make a thoroughly clean cut.

The making of such previous fasteners has required an excessive length of blank strips, and the cutting away of an undesirably large amount of material to form the cutting edges and throats.

The making of the rounded corrugations has also caused the forming rolls to constantly wear out of shape.

The making of the rolls for forming the rounded corrugations is difficult on account of the necessity of having specially shaped cutters which must be accurately ground.

It has been the object of my invention to overcome these objections, and they are eliminated more or less completely by the embodiment of my invention by which I shall illustrate it.

In the illustrated embodiment, I provide a strip of sheet metal l, which is corrugated by forming comparatively sharp V-shape bends 2, connected bysubstantially straight or plane portions 3. The cutting edge of the strip consists of chisel-shape points 4 substantially at the middle of each Vof the straight inclined portions 3, said points preferably being formed by bevels 5 and 6, one on each side of the cutting edge of the point. A notch 7 is formed between eaclr two chisel points, and'has substantially straightline cutting edges 8, which meet at a point at the crest of the corrugation, and which are formed by outer and inner beveled surfaces 9 and 10.

rlhe construction of the fastener will perhaps be more thoroughly understood by a brief description of a process of making it. According to the process which 1 prefer, l take the strip of metal of which the fastener is to be made, and while it is yet straight, and before it has been corrugated, ll bevel the edge which is to form the entering edge of the fastener. rlhe edge is preferably beveled on both sides of its median line. rllhis beveling, being done while the strip is flat, may be done by shaving with stationary or oscillating knives, by milling, or by grinding. rlhis first operation forms the edges 4 of the chisel points, and their beveled faces 5 and 6. The strip is then corrugated to form the V-shape corrugations 2, connected by the straight portions 3, after which the inclined surfaces 9 are formed by cutters moved in planes inclined to the vertical, which cut away the corners of the outward bends of the corrugations, together with the adjacent parts of the fiat portions 3, this operation both forming and sharpening the notches between the chisel edges. rlhe length of the chisel edges is determined by the depth of the cuts forming the notches and the chisel edges can be reduced to mere `points by causing these cuts, upon opposite sides, to meet at the median line.

My fastener has, among others, the following advantages:

'lhe entire entering edge of the fastener is a cutting edge; that is, not only do the points t have chisel shape edges through-l out their length, but the edges of the notches are beveled from point to point and form cutting edges. v

'llhe chisel points being formed by a double bevel (that is, by an inclined surface on each side of the cutting edge), enter the wood much more easily than do the chisel points which are formed by the meeting of a single beveled surface with a vertical surface. Moreover, with a given size of corrugation the chisel points tend less to tear the wood, because they are more nearly in line with the direction of the grain, than is the case when rounded corrugations are used which enables them to penetrate between the fibers of the Woodinstead of having to cut across the grain.

The edges of the notches being substantially straight lines and meeting at a point Lacasse at the bottom of the notch, cut to much better advantage, because the lcutting edge is sharply inclined to the horizontal and nowhere is horizontal.

The cutting edges 8 of the notch are formed by the meeting of twobeveled surfaces, namely, the original bevel on the inside of the corrugations and the bevel 9 on the outside thereof, and thus they are able to penetrate most eHectively. Moreover, as the cutting edges 8 are inclined pretty nearly in the general direction of the grain, as well as inclined to the vertical, the danger of tearing the wood and breaking the grain is reduced to a minimum as is also the force required to drive them into the wood. The removal of the metal to form the notches eling of the edge of the strip, the thickness of the chip removed to finally form the notches is less than it would otherwise be.

Although the notches are sharp throughout, they do not have to be deep in order that they may be sharp, and thus thewidth of the strip may be reduced to a minimum in forming the notches, and the strip has a very large proportion of its original stren h.

rllhe length of material used for making fasteners is less with my corrugated fastener than with one made up entirely of curves, and the length of the cutting edge is correspondingly reduced.

When the ll-shape corrugations are used in combination with the form of cutting edge which l have illustrated, a very marked advantage is obtained, both as to the amount of power required to drive the fastener vand the cleanness with which it enters the wood, and for these reasons they are more easily driven straight.

On account of the corrugations being sharp bends, they leave the `wood between them in stronger shape than the curved fasteners, the wood being solid clear up into the bends instead of being crushed away from the bends as frequently happens with fasteners having rounded bends. This means that the wood is in better condition to hold the fasteners so that a joint of greater strength is obtained. v l

The rolls used to formthe ll-shape corrugations wear much longer`than those used to form rounded corrugations, sincethe rolls for forming rounded corrugationsV tend to assume the shape used for the lf-shape corrugations. l

The making of rolls for forming the V-shape corrugations is cheaper than the making of rolls for forming the rounded corrugations, since the latter require specially shaped cutters which must be accurately ground, while the former are made by ordinary angle cutters, which are easily ground.

On account of my corrguations being V- shape instead of rounded, they nest together more perfectly when a strip is wound into a coil, so that the greater length of strip can be wound in a coil of a given size, thus allowing a fastener driving machine to be run considerably longer without stopping toreplenish the coils.

No portion of the cutting edge of my fastener extends directly across the grain of the wood at any point when the fastener is driven to unite two boards placed side by side.v Since the curved corrugations tend to mash down the grain of the wood because they'lie across the grain, they tend to cause their fasteners to tip both crosswise and lengthwise of the grain, and thus frequently result in failing to drive the fasteners in the position in which they were intended. As the cutting edge of my fastener, however, at no point lies across the grain, this diiiculty is avoided.

I claim:

l. A fastener comprising a corrugated strip of metal having a rentrant portion at each apex, and chisel points alternating with the said rentrant portions.

2. A fastener comprising a corrugated strip of metal having a rentrant portion at each apex, and chisel points alternating with the said reentrant portions, both said chisel points and the entire edges of said reentrant portions being sharpened.

3. A fastener consisting of a strip of corrugated sheet metal, eac corrugation having on its entering edge. chisel points inclined to the length of the fastener, said points having edges formed by the meeting of two beveled surfaces.

4L. A fastener consisting of a corrugated strip of metal, having on its entering edge chisel points inclined to the length of the fastener, the cutting edges of said points being formed by the meeting of two beveled surfaces, and rentrant portions having` cutting edges, being formed respectivelyr between the chisel points.

5. A fastener consisting of a corrugated strip of metal, each corrugation having on its entering edge chisel points inclined to the length of the fastener, the cutting edges of said points being formed by the meeting of two beveled surfaces, and rentrant portions having cutting edges, the Tcutting edges of said rentrantportions being in substantially straight lines.

6. A fastener consisting of a corrugated strip of metal, having on its entering edge chisel points inclined to the length of the fastener, the cutting edges of said points being formed by the meeting of two beveled surfaces, and rentrant portions having cutting edges formed by an additional beveled surface.

7. A fastener comprising a corrugated strip of metal whose entering edge is beveled on both sides throughout its Whole extent, the edge of each .corrugation being formed of alternate portions at dierent levels.

8. A fastener comprising a corrugated strip of metal whose entering edge is beveled on both sides throughout its Whole extent, the edge of each corrugation being formed of alternate portions at different levels, the angles of the bevel of said different portions being substantially the same.

9. A fastener comprising a strip of sheet metal having a cutting edge composed of V-shape notches with substantially straight connecting portions, and having a chisel shaped point substantially at each of said straight connecting portions.

l0. A fastener comprising a strip of sheet metal having a cutting edge composed of V-shape notches with substantially straight connecting portions, and having a chisel shaped point substantially at each of said straight connecting portions, said notches having cutting edges extending from said points.

11. A fastener comprising a strip of sheet metal having a cutting edge composed of V-shap'e notches With substantially straight connecting portions, having a chisel shaped point substantially at each of said straight connecting portions, said notches having substantially straight cutting edges extending from said points.

l2. A fastener comprising a strip of sheet metal having a cutting edge composed of V-shape notches with substantially straight connecting portions, having a chisel shaped point substantially at each of said straight connecting portions, said notches having cutting edges extending from said points, said chisel points having their cutting edges formed by the meeting of two beveled surfaces.

13. A fastener comprising a strip of sheet metal having a cutting edge composed of V-shape notches with substantially straight connecting portions, having a chisel shaped point substantially at each of said straight connecting portions, said notches -having cutting edges extending from said points, both said cutting edges and said chisel shaped points being formed by the meeting of oppositely beveled surfaces.

14. A fastener comprising a strip of metal having a cutting edge composed of V-shape notches connected by straight portions, such straight portions having chisel points substantially at the middle thereof, said notches having cutting edges extending from said chisel points and meeting at a sharp angle 15. A fastener comprising a series of corrugations having notches at the apex of each corrugation, and cutting points between said notches, the entire cutting edge being sharpened.

16. A fastener comprising a series of V- i shaped corrugations having notches at the ape-X of each corrugation, and cutting points yL L j insges@ FRANK l). PRINDLE. Witnesses:

S. W. PARSONS, WV. E. DOANE. 

